The invention relates to slack rope detecting apparatus primarily for use in mining equipment.
Drum winders are used extensively in the mining world for the lowering and raising of men, material and ore, in shaft systems. When a cage does not travel at the same speed as the wire rope coming off the winder drum a slack rope develops.
Should sufficient slack rope be generated it is possible that the wire rope can become severely kinked, and either the rope itself or attachments between the wire rope and the cage can fail in tension due to severe overloading when the cage begins to fall freely, and is suddenly retarded when it has taken up all the slack in the rope that has been paid out.
There is also a problem in rope winding operations when starting a mine cage or mine car down a vertical shaft or incline in that the load may not immediately move or moves more slowly than anticipated. The winding engine can over-run the speed of the load and produce slackness in the rope. In extreme cases subsequent acceleration of the load takes up the slack and overstrains the rope or even breaks the rope or the anchoring between the rope and the load.
Slack ropes on winding plant can occur quite frequently and there have been several fatalities due at least in part to such occurrences.
Mechanical arrangements are already known for use in mining operations and domestic lifts which are generally arranged to jam the load if the load sticks and/or the rope slackens so that the overstrain or breakage mentioned above cannot occur.
It is an object of the invention to provide a slack rope detecting apparatus in the form of an electrical circuit arrangement which is generally more reliable and safer than earlier arrangements.